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25 Nov 2013, 00:41

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Can anybody help me explain this question.

Scientists at the Los Alamos National Laboratory have succeeded for the first time in mining heat from the Earth’s interior and producing energy on a commercial scale, enough for efficient generation of electricity and heating factories and homes.

A. and producing energy on a commercial scale, enough for efficient generation of electricity and heatingB. and producing enough energy on a commercial scale for electricity to be generated efficiently and to heatC. for energy production on a commercial scale, enough for generating electricity efficiently and to heatD. to produce energy on a commercial scale, enough for generating electricity efficiently and for heatingE. to produce enough energy on a commercial scale for efficient generation of electricity and heat
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Scientists at the Los Alamos National Laboratory have succeeded for the first time in mining heat from the Earth’s interior and producing energy on a commercial scale, enough for efficient generation of electricity and heating factories and homes.

A. and producing energy on a commercial scale, enough for efficient generation of electricity and heatingB. and producing enough energy on a commercial scale for electricity to be generated efficiently and to heatC. for energy production on a commercial scale, enough for generating electricity efficiently and to heatD. to produce energy on a commercial scale, enough for generating electricity efficiently and for heatingE. to produce enough energy on a commercial scale for efficient generation of electricity and heat

Note that there are two elements logically parallel here.

energy is produced on a commercial scale for two things:1. efficient generation of electricity2. heating factories and homes

They should have parallel structure.

A. and producing energy on a commercial scale, enough for efficient generation of electricity and heating (should be 'generating electricity and heating')B. and producing enough energy on a commercial scale for electricity to be generated efficiently and to heat (should be 'to generate electricity and to heat'C. for energy production on a commercial scale, enough for generating electricity efficiently and to heat (again, generating and heating) D. to produce energy on a commercial scale, enough for generating electricity efficiently and for heating (correct)E. to produce enough energy on a commercial scale for efficient generation of electricity and heat (should be 'to generate and heat')

Only (D) gives you the correct parallelism.

Also note that 'mining heat from the Earth’s interior' and 'producing energy on a commercial scale' are not two independent parallel actions. One is dependent on the other. They mine heat to produce electricity. This is a meaning issue.
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